Preparation of pressed sugar tablets



United States Patent 3.255.041 PREPARATIGN 0F PRESSED SUGAR TABLETS Eimer .l. Culp, Harrison, and Robert Max Gerstenkorn,

Red Hook, N.Y., assignors to American Sugar Company, New York, N.Y., a corporation of New Jersey No Drawing. Filed May 22, 1964, Ser. No. 359,577 13 Claims. (Cl. 12763) This invention relates to pressed sugar tablets. Particularly the invention relates to a process for preparing hard, pressed sugar tables having a white, sparkly appearance.

Sugar compositions in tablet or cube form have long been an article of commerce. The manufacture of ordinary pressed sugar tablets is a relatively simple and fast operation. It requires only that an admixture of granulated sugar and colorless sugar syrup be supplied to a tableting machine, such as a Hersey machine wherein a rotatable cylinder is provided with a series of pockets extending inwardly into the body of the cylinder. These pockets serve ,as molds for receiving the sugar admixture. Slidably fitted within the pocket and constituting the bottom thereof is a plunger which is mounted in the cylinder for reciprocating movement. The arrangement is such that the plunger is advanced toward and retracted away from the concave face of a pressure plate located closely adjacent a portion of the cylinder surface and against which the sugar mixture in the pocket is pressed or compacted to produce the desired shape. The plunger also serves to force out the pressed sugar mixture from the pocket onto a tray or conveyor belt. The resulting pressed sugar tablet is then dried in a bakery type oven and packaged. The drying operation commonly takes from about 1 hour at 200 F. to about 4 hours at 120 F. (A more complete description of the operation of a tableting machine is set forth in US. Patent 1,836,604.)

These ordinary pressed sugar tablets, after drying are relatively hard, easily soluble, smooth edged and possess surfaces having a dull appearance. They lack the sparkle and hardness of crystal sugar tablets made by the Adant process.

Crystal sugar tablets made by the Adant process have an appearance strikingly different from ordinary pressed sugar tablets. Crystal sugar tablets made by the Adant process present a rough, uneven surface, are hard and shiny and full of sparkle. In the Adant process coarse grained magma is transferred directly from the pans into large molds and allowed to cool and harden for about 20- 30 hours. The sugar crystals grow while in the mold and at the end of the molding operation, large shiny sugar crystals have formed. The molds are then placed in a centrifuge and excess liquid is spun off. The moist slabs are dried and then mechanically cut to yield the crystal sugar tablets which are very hard, uneven surfaced, shiny and full of sparkle.

The manufacture of crystal sugar tablets by the Adant process is an expensive operation because of the number of processing and handling steps involved and due to the losses incurred during the mechanical cutting operation. Breakage during the mechanical cutting operation is substantial and contributes to the cost of the finished product.

It is an object of this invention to provide a process for the manufacture of a pressed sugar tablet of improved hardness and sparkle.

Another object of this invention is to provide a pressed sugar tablet approaching the quality of a crystal sugar tablet made by the Adant process.

Still another object of this invention is to provide an inexpensive, high productivity method for the manufacture of a pressed sugar tablet.

A preferred object of the invention is a process for making a pressed sugar tablet having these characteristics: the cool dry tablet having a hardness suflicient to with- Patented June 7, 1966 ice stand handling and the forces of automatic packaging machinery without crumbling or breaking; a water content of less than about 1 weight percent, preferably about 0.5 weight percent; a white, sparkly appearance; sharp edges; and good weight control.

How these and other objects of this invention are achieved will become apparent in the light of the accompanying disclosure of the manufacture of pressed sugar tablets in accordance with this invention.

It is to be understood that tablet includes any regularly shaped form which may be made by pressing of a moist sugar-syrup admixture, such as a tablet, cube or load. Conventional commercial shapeshave the following dimensions: /2 'inch cube; 1 /2 inch, inch by inch; 1 inch, 3; inch by 4 inch.

Broadly the process of the invention comprises: for. ing a moist pressed sugar tablet having a water content of about 1.62.8 weight percent; rapidly bringing said moist tablet to a temperature of about 200230 F. by means of infra red radiant energy under conditions of energy intensity and time such that no significant amount of caramelization occurs; substantially immediately thereafter decreasing the temperature of said hot tablet, said rate of decrease being controlled by infra red radiant energy, to a temperature of about 150-180 R, where the time of residence of said hot tablet in this second zone is that time necessary to obtain a tablet water content of less than about 1 weight percent; and thereafter cooling said dry tablet to a temperature of below about F. at a rate such that a hard, dry tablet is produced.

Preferably the warm dry tablet is cooled, after it has reached the desired water content, by means of forced cool dry gas. i

In the preparation of the sugar admixture any refined sugar grain, such as tablet sugar may be employed. This sugar may be mixed with-sugar syrup and/or water to form the mixture which is charged to the tableting ma* chine.

It has been found that the dry pressed sugar tablet has the desired white, sparkly appearance when the Water content of the moist pressed tablet is controlled to be between about 1.6 and 2.8 weight percent.

The dry tablet must have a water content of less than about 1 weight percent and, more desirably, less than about 0.5 weight percent.

Infra red radiation is utilized as the heating means in the process of the invention. Herein infra red radiation is intended to mean radiant energy having a wave length in excess of about 7000 Angstrom units or, more commonly, in the range of 7000-20,000 Angstrom units.

The desired sugar tablet is obtained when the infra red heating of the moist tablet is carried out in a particular manner. In the process of the invention, the defined moist tablet is brought to a temperature of about 200 230 F more commonly 215230 F., by means of infra red radiant energy. The intensity of the radiation and the time neededto reach the aforesaid temperature is controlled so that no significant amount of caramelization occurs. Time will vary with the size and shape of the tablet, but for commercial size tablets is approximately 14 minutes, approximately 11-2 minutes at the higher temperature range. A somewhat longer time is permissible at the lower temperatures and a somewhat shorter time is needed at the higher temperatures.

The hot moist tablet, now at about 200-230 F., then has its temperature gradually dropped to between about and about 180 B; said temperature drop being controlled by another infra red heating operation. The other infra red heating operation follows substantially immediately after the higher temperature infra red heating operation. It is preferred that the tablet water content be about the desired amount when the temperature of the tablet has reached the loW temperature of the infra red water removal zone. However, in any case, the tablet is maintained at about 150-180 F. by infra red radiant energy until the water content has decreased to the desired level of less than about 1 weight percent, and preferably less than about 0.5 weight percent.

The time necessary in the other infra red heating operation is determined by the water to be removed, the temperature of the tablet in the lower temperature water removal operation, and somewhat on the size and shape of the tablet. For ordinary commercial size tablets, this water removal period of infra red heating is approximately 2-4 minutes, with the period varying according to the aforementioned factor.

The temperature of the warm tablet emerging from the infra red water removal operation is quickly lowered to below about 130 F.the cooling rate being controlled to produce a hard tablet, normally; by contacting the warm tablet with a stream of cool dry gas, whose temperature is below the temperature to which it is desired to cool the dry sugar tablet, Air is a preferred gas. It is desirable to cool the tablet to a temperature of about 90-110 F. It is preferred to introduce the cool dry gas at a temperature of about 4090 F. The forced cooling operation produces hard tablets in a fraction of the time needed when the tablets are exposed only to atmospheric cooling.

It has been observed that the cool dry tablet continues to increase in hardness for some time after leaving the cooling zone. Thus the hardness of the tablet in the package is not the standard for determining the necessary hardness of the tablet leaving the cooling zone. It has been found that the cool dry tablet is sufficiently hard if the tablet cannot be crushed by squeezing it between the thumb and forefinger and inspection of a tablet which has been snapped in two shows a hard center and little crumbling of edges at the break.

In the continuous process where the defined moist tablet is rapidly heated to about 200 -230 F.; substantially immediately thereafter the hot tablet is passed to the water removal operation i.e. the second zone, where it reaches an emergent dry temperature of about 150180 F. at a water content of less than about 1 weight percent; and substantially immediately thereafter in the cooling zone, the warm dry tablet is cooled by a stream of cool dry air, at about 40-90 F., to a temperature of about 90110 F., a hard, sparkly white tablet is produced in a total heating and cooling time of between about 5 and minutes. When operating the higher temperature zone at about 215-230 F., the total time is between about 6 and 8 minutes.

Test I In an operation using Goka infra red dryingsingle stage moist cubes containing about 1.2% water were dried to water contents of 0.61 .0%. The dry cubes emerging from the the drier had a chalky lackluster appearance and suffered excessive crumbling (erosion) of the edges under mild handling. These cubes had to be aged 34 hours before they were hard enough to be packaged.

Test II A Goka infra-red drierwas modified to permit reaching various temperature levels. This drier had a hot section with infra red radiation providing 0.48 kilo-watts per square foot (kw./sq. ft); a forced air cooling section; and an ambient air cooling section. A conveyor belt carried the cubes on trays continuously through the three sections. The residence time in the hot section was determined by the final temperature. The entire time in the drying operation was held at 22 minutes. The water content of the moist cubes was very close to 3.0 wt. percent. With the hot section arranged to give a cube temperature of about 220 F., the water content of the dry cubes was 1.0%. With a hot cube temperature of about I 260 F., the water content was 0.4%. However, in all cases the dry /2 inch cubes were too soft and showed excess color buildup, i.e., significant caramelization had occurred. Also; in the higher temperature runs, the cubes showed evidence of melting.

Example 111 In this example a three zone drier was used. This had a hot section using 1.75 kw./ sq. ft. of infra red radiation; a lower intensity section using 0.50 kW./ sq. ft. of infra red radiation energy; and a forced cooled dry air cooling. section. The /2 inch cubes were carried on a conveyor belt continuously, passing immediately from one section to the next section.

Moist cubes having a water content of 2.28% were passed into the hot section; with a 2 minute residence time, the final hot cube temperature was 220 F. The hot cube was passed into the middle section and in a residence time of 2 minutes, the temperature dropped to 160 F. After a 2.4 minute cooling time, the water content was 0.65%. The dry cubes were satisfactorily hard and had a bright sparkly appearance.

Example IV This example was carried out as in Example III. The moist cube contained 2.36% water; the dry cube contained 0.91% water. The 'hot cube temperature was 210 F.; the cube from the middle section was about 160 F.; the cool dry cube was 98 F.; and the cooling dry air was at F. The total time was 7.5 minuteshot section, 1.8 minutes; middle section, 2.0 minutes;

cooling section, 3.7 minutes. The dry cubes were rated perfect in all requirements.

Thus having described the invention, what is claimed is:

1. A process for preparing pressed'sugar tablets which process comprises:

forming a moist pressed sugar tablet having a water content of about 1.6-2.8 weight percent;

rapidly bringing said moist tablet to a temperature of about 200230 F. by means of infra red radiant energy under conditions of energy intensity and time such thatno significant amount of caramelization occurs;

substantially immediately thereafter decreasing the temperature of said hot tablet, controlling said rate of decrease by infra red radiant energy, to a temperature of about 150180 F., where'the time of residence of said hot tablet in this zone is that time necessary to obtain a tablet water content of less than about 1 weight percent; and

thereafter cooling said dry tablet to a temperature of below about F. at a rate such that a hard tablet is produced.

2. The process of claim 1 wherein said moist tablet has a residence time in said high temperature zone of about 1-4 minutes, where the shorter time is associated with the higher temperature.

3. The process of claim 1 wherein substantially immediately after said hot tablet has reached the desired Water content, said dry tablet is cooled by means-of forced cool dry gas'until a hard tablet is produced.

4. The. process of claim 3 wherein said dry tablet is cooled to a temperature of about 90-110 F.

5. A continuous process for preparing pressed sugartablets which process comprises:

forming pressed sugar tablets having a water content of caramelization occurs;

rapidly heating said tablets by means of infra red radiant energy to a temperature of about 200-230 F. under conditions such that no significant amount of carmelization occurs; substantially immediately thereafter passing said hot tablet into another infra red heated zone wherein the temperature of said hot tablet is controllably decreased to about 1;80 F. and said hot tablet is maintained in said other zone for a time such that the water content of the tablet is decreased to less than about 1 weight percent; and substantially immediately thereafter passing said warm, dry tablet into a cooling zone wherein forced, cool dry gas decreases the temperature of said tablet to below about 130 F. at a rate such that hard tablets are produced. 6. The process of claim 5 wherein said cool dry gas is air.

7. The process of claim 5 wherein the temperature in said higher temperature zone is about 215230 F.

8. The process of claim 7 wherein the time in said higher temperature zone is approximately 1-2 minutes.

9. The process of claim 5 wherein said cooled dry tablet is at a temperature of about 901l0 F.

10. The process of claim 9 wherein said cool dry gas is at a temperature of about 4090 F.

11. The process of claim 9 wherein the total time of heating and cooling is between about 5 and 10 minutes.

12. A continuous process for preparing pressed crystal sugar tablets, which process comprises:

forming moist pressed sugar tablets having a water content of about 1.6-2.8 weight percent;

passing said moist tablets through an infra red radiant energy heating zone wherein said moist tablets are heated to a temperature of about 215 230 F. in a time of approximately 12 minutes;

passing said hot moist tablets into another infra red radiant energy heating zone wherein said tablets are controllably brought to a temperature of about 150"- 180" F. and said moist tablets are held Within said other zone until the water content thereof has been lowered to below about 1 weight percent; and

passing said warm dry tablets into a cooling zone wherein forced, dry gas at an entry temperature of about 90 F. rapidly cools said dry tablets to a temperature of about -110 F.

13. The process of claim 12 wherein said total time of heating and cooling is between about 6 and 8 minutes.

References Cited by the Examiner UNITED STATES PATENTS 3,169,888 2/1965 Ryan et al. 127-63 MORRIS O. WOLK, Primary Examiner.

M. E. ROGERS, Assistant Examiner. 

1. A PROCESS FOR PREPARING PRESSED SUGAR TABLETS WHICH PROCESS COMPRISES: FORMING A MOIST PRESSED SUGAR TABLET HAVING A WATER CONTENT OF ABOUT 1.6-2.8 WEIGHT PERCENT; RAPIDLY BRINGING SAID MOIST TABLET TO A TEMPERATURE OF ABOUT 200*-230*F. BY MEANS OF INFRA RED RADIANT ENERGY UNDER CONDITIONS OF ENERGY INTENSITY AND TIME SUCH THAT NO SIGNIFICANT AMOUNT OF CARAMELIZATION OCCURS; SUBSTANTIALLY IMMEDIATELY THEREAFTER DECREASING THE TEMPERATURE OF SAID HOT TABLET, CONTROLLING SAID RATE OF DECREASE BY INFRA RED RADIANT ENERGY, TO A TEMPERATURE OF ABOUT 150*-180*F., WHERE THE TIME OF RESIDENCE OF SAID HOT TABLET IN THIS ZONE IS THAT TIME NECESSARY TO OBTAIN A TABLET WATER CONTENT OF LESS THAN ABOUT 1 WEIGHT PERCENT; AND THEREAFTER COOLING SAID DRY TABLET TO A TEMPERATURE OF BELOW ABOUT 130*F. AT A RATE SUCH THAT A HARD TABLET IS PRODUCED. 